Hydraulic apparatus, particularly for vehicle stabilizing equipment



Sept. 5, 1950 L. B. LYNN ET AL 2,520,944

HYDRAULIC APPARATUS, PARTICULARLY FOR VEHICLE STABILIZING EQUIPMENT Filed Nov. 20, 1947 4 Sheets-Sheet 1 /02 9 web /07 Q .B I /.57 I56 WITNESSES: INVENTOR 5 v c ,Q/ LawrenceBynn and W 5fi?/eyfMll fna. 2a)- 8 Win/1m ATTORNEY Sept. 5, 1950 L B. LYNN ET AL 2,520,944

HYDRAULIC APPARATUS, PARTICULARLY FOR VEHICLE STABILIZING EQUIPMENT Filed Nov. 20, 1947 4 Sheets-Sheet 3 Fig 7 gm ,/"Z04 2/9 2/5 x 2/7 264G262 I03 "/23 0 H ZZh- WITNESSES: L BAINVENTORSOI r awrence ynn on 54 2 v 5fa /e zM/mh 73/ ME, W

- ATTORNEY 1.. B. LYNN ET AL 2 520 944 Sept 1950 HYDRAULIC APPARATUS, PARTICULARLY FOR VEHICLE STABILIZING EQUIPMENT 4 Sheets-Sheet 4 Filed NOV. 20, 1947 ,0 s m a v QQN, R V: o n 1 E M n N 30m w/WM m fiwm ax n w W/ A 0 MY e E r a g M Q r A F 909% Qmm iu n 4 \NQ \wom I own -.mmm mmm .lum m .wmm Now WITNESSES:

Patented Sept. 5, 1950 HYDRAULIC APPARATUS, PARTICULARLY FOR VEHICLE STABILIZIN G EQUIPMENT Lawrence B. Lynn, Wilkinsburg, and Stanley J.

Mikina, Pittsburgh, Pa., assignors to Westinghouse Electric Corporation, East Pittsburgh Pa., a corporation of Pennsylvania Application November 20, 1947, Serial No. 787,230

16 Claims.

Our invention relates to hydraulic apparatus and, more particularly, to complete hydraulic systems as well as to valve devices for controlling the performance of such systems. In one of its specilc aspects the invention relates to hydraulic apparatus for stabilizing purposes, for instance, to ride stabilizers for vehicles.

The invention involves improvements over hydraulic systems and hydraulic control devices of the kind disclosed in the copending applications Serial No. 509,314 of C. R. Hanna, Serial No. 623,368 of L. B. Lynn and C. R. Hanna, and Serial No. 794,145 of L. B. Lynn, all assigned to the assignee of the present invention. Application Serial No. 509,314 issued on Jan. 3, 1950 as Patent No. 2,492,990.

It is an object of our invention to devise hy=- draulic apparatus that, in comparison with apparatus previously disclosed, permits selecting the inherent amplification factor within a much wider range, and permits obtaining a much larger amplification than heretofore possible. It is also an object of the invention to afford re-. ducing the idling losses of the system for a given amplification factor. A further object is to permit employing a condition responsive pilot mechanism of lower time constant than previously applicable.

Another object of our invention is to provide hydraulic apparatus capable of a controlled performance similar to that of the systems previously disclosed while requiring as a power source only one pump instead of the two pumps heretofore necessary in the older systems.

According to one feature of the invention, we connect a variable-volume space of a hydraulic device to be controlled to one of three openings in a cavity of a device whose other two openings are in communication with the pressure and re-' turn ducts respectively of a pump or other source of a flow of liquid under pressure, and we provide the control device with two interconnected valve members which vary the flow area or flow resistance values of the two latter openings in inverse relation to each other through a range of continuous variation between finite magnitudes.

According to another feature of the invention, we employ a hydraulic motor or other device which has a pair of pressure ducts and is controlled by the difference in the hydraulic pressures applied to the respective ducts, and we connect this device to the duct pair of the hydraulic power source through a control device which has two cavities in free communication with the respective ducts of one duct pair, each cavity having two flow-restricting openings in always open communication with the respective ducts of the other duct pair so that the two cavities form hydraulically parallel arranged 2 paths for the flow of liquid from one to the other duct of the other duct pair; and we provide the control device with interconnected valve structures which control the flow of liquid through said respective paths in inverse relation to each other. According to a more specific feature of our invention, we provide each cavity with two valve elements for controlling the above-mentioned two openings respectively, so that the control device includes a compound valve mechanism with four interconnected valve elements which are open during all phases of normal operation but vary their respective flow areas or flow resistances in the above-mentioned relation to one another when actuated.

These and other objects and features of the invention will be apparent from the following description in conjunction with the drawings, in which:

Figure l is the hydraulic circuit diagram of apparatus according to the invention shown, simplified and schematically, for the purpose of explanation;

Fig. 2 is a modified form of apparatus according to the invention especially designed as a ride stabilizer for vehicles and represented diagram matically in a manner similar to the showing of Figure 1;

Fig. 3 shows schematically a vehicle equipped with ride stabilizing apparatus according to Fig. 2;

Figs. 4 to 8 illustrate details of a control device for ride stabilizers, according to Figs. 2 and 3; more specifically: Figs. 4 and 5 show two respective cross sections of the device takenat a right angle to each other;

Fig. 6 shows another section taken along a 4 plane denoted in Fig. 5 by the section line VI VI; Fig. 7 shows part of the device in a view taken from the right of Fig. 5 onto the sectional plane denoted by line VII-VII in Fig. 5;

Fig. 8 shows a cross section through a detail of the device appearing in the lower right corner of Fig. 5, the section plane of Fig. 8 extending at F a right angle to the plane of illustration of Fig. 5;

Fig. 9 is a part-sectional illustration of an other modification of apparatus according to the invention designed for adjusting a cam member of the fabricating machinery; and

Fig. 10 is an explanatory hydraulic circuit diagram of the apparatus according to Fig. 9.

In Fig. 1 the hydraulic device to be controlled is schematically represented as a motor i with two pressure ducts or conduits 2 and (-3 which lead into respective pressure spaces of motor 5. The operation motor I is controlled by the difference in the pressures ofv the two ducts. The pressure for operating the motor is provided by a suitable pressure source, such as a positive displacement pump 4 with a pair of ducts 5, 6 for circulating 3 liquid under pressure the pains may ep rat at constant speed fr constant volumetric d'elivery. In the diagram of Fig. 1, duct 6 is as sumed to represent the pressure or outlet duct, While duct is the neutrallhfr the. Yitiith duct.

Duct 6 branches into two ciihduits- N1 and 6h. Interposed between the pressure source 4, and

c it a n s a valve opening I I, ecn'trolieq by a notate valve elemeht l2 and in c meme-awith the sump conduit 61). Another valve jg. 13 ct cavity 3 is controlled by a movl'rn'eht I i and 'eemmue -eates with the reljil -(skin digit 5 Of the p m Similarly, the davitil 9, has st rve ri ning It "controlled by a movable valve e1efiien't 1'6. and inh'orhr'nijihicatibh with the conduit. 32;, and another opening I! ebiitienea by a'inovabie valve elem nt 18 and in communication with tl'i'e return "duct 5. The gene; elements [2 and 1'4, are terme b3? 'valve races of a hbd y i2 2, and the valve e1 '1r1e'uts lt and body 23. Bodies 22 and. 23, are intercqn' n'e ted By (55 24. moveieenter. red 2! is line ea tea to, 56th valve bodies so that the new areas Hf the 'fbilr valves are simultaneously varied in a fixed relation to one another In any verve positibi the flow area at epeeip II is i'prefntry equal to that at opening ll, and the new area at alve opening it is lpreferab'ly equa to that at eee'mng [5. The ani'pli'ficatibn ras er er the control apparatus depends upon the. differencebetween the new area (A1): at veji opening H at and the new area (A2) at opening l3-or L1, and is a maximum when both. areasare equal, as wni beset 'forthin a later place.

Assumin that the new of l iiiuid impelled by the. ioume 4 i in the direction 6: the 'arrows, a continuous circulation bccurs hem. conduit '65 I through cavity 8 to duct 5, and another 'ciontfj ous circulation eizists from conduit 62: th test 9. to duet a. censegeentiy theit'wt 'e'e a and '9fare arranged in hydraulic para el e1 ties to each other betweeeltiie tweuue'ts san 6 qf the hydraulic sewer "sburc'e. V

'7 When the valve bodij 5 22am 'z's 'a're. the illustratednormal position, th ne a a ei ree sistance to fluid, flow at. lening ll is equal to the Corresponding magnitude at opening [5-, and the flow area or resistance at valve opening '13 is equal: to that at valve oiaen ing I 'l.. -llifiruiier these conditions, the magnitudes, of fluid new in'the two cavities are the,s'ame and,the pressures built up in the two cavities and applied to the respec tive. ducts of the motor I are also thefisa'ine. Consequently, the differential. "ptese ie en; the motor is zero. and the motor remains at rest.

When the valve structure, by some control eleine'nt not illustratedin Fig. 1., is 'r'nojved us-ti er V the flow areas at valve openings It and. lfl --ar e reduced and the 'lc'orres'pon'din'g areas -aft vfal v 'e openings IB-and 15 are increased. a re'sult,

the-pressurein cavity 8 decreases, whilethepreise sure in cavity 9 increases. Accordinglmth'e This device has two tihafmhers '8 cbiisis t of valve rates an another "verve atcdei rhbtol? duct it assumes high pre sure and the duct 2 16W ressure, so that the motor is actuated in the correspondin direction of movement. When the valve structure is moved downwardly from the. illustrated position, the valves change their new areas and new resistances in the opposite sense so that the pressure in cavity 8 is increased and the pressure in cavity 9 decreased. The cbri esponding' pressure difference acting on the motor I then causes the motor to produce movement in the opposite direction.

is'liifiize each er the four individual valves when changing its flow area has a pressure controlling efiect on the difierential pressure applied to the metor, it will be, recognised that. a compound valve with four individual val've unit's, properly ee-re1atee as explained above, has a correspond= ihgl y mllliti t the "met, the above described eperetien resuhstahtially the same except that the pressures. in, cavities '8 and '9 and the direction ermevement in motor 1 are reversed. Another modification consistsin an exchan e cf sewer source and motor. That is, the inqtor may be connected at the illustrated place of the pump, while the pump placed at the illustrated locatiiin df the motor. As will he understcod --frei n the diagram -of Fig. 1c explained below, it is also ss'jible to connect the two pressure conduits 2 and 3 to two individual 'mbtors so that the control 'dffea'ch motor is effected by enly one 'valve :lfiiiidy with two indiv'mum valve elements dispdse'd Ina single cavity.

The hydraulic apparatus diagrammatically re; resenf'tedfin Fig. 2 is'especi-ally designedfer the control "of stabilizing equipment, in particfilar for stabilizing the spring suspended body of a veeieie. The device to be controlled is denoted as a miei by r01 it'eensists of a cy l-inder=and piston e or 'ade'sign similarto custcinary hydraulic gabs'orbe'rs. The device is con-trolled by the difference in the pr ssures applied to pair or ducts or conduits W2, @155. The necessary-squid under pressure is provided by a positive displace- "ment pump ts which has a return duet ms and 'afpres dre duct 163, The pressure duct 'l flfiis Split i'rlto two branch, "conduits H161) and 1-950. Disposedfbetween pump and controlled device lfl'lfi's a pilot app rat s ifil wrrese housing struc tuie has two eavitie tfeee d gee. Cavity ite ha's twogv ve openings lflland "l is in communication iththereSpGct'iVE prim-p ducts lett r-1c l fts and 'FiQli '"blled bytw'o'valv'e faces of a valve bed IP12; lll fih'a'stwo valve openings 11% andjl l l-in c'tiiiiihunication with conduits 'lilfic and respectively, andcontrolled by valve faces of a valve bc'dir "I23. The bodies 122 and 123 are interconnetted bya 'ro'd 25. Thecontrdldevice 1 0 enclds'es a 'fiutral plesslfiefspace 1253 which is in freeicom'r'i 'unication with the return conduit 1 st and with 'the valve openings [13 and "H 7. An in'erti'a weight 1251s r'ern'ov'ably suspended within the. neutral pressure space [253. Weight 12 5 TS ri'i'diint dfdn an ar 1 25 which is pivoted "about ia'shaft I21 and linked to the connecting rod 1 2 i.

iw'ei'ght I25 is normally held in center posiby means Of biasing springs.

"cdr'ilti'olled stabilizing cevi e "it! ha a eyuficer IZB'With'tW'O eist'ens [3 0 and BI which form, together with the cylinder, two pressure spaces I32 and I33, respectively, and'in intermediate neutral space I34. The neutral space is connected by a conduit I35 with the neutral space I of the control device IO'I'and with the return conduit I115 of the pump. The neutral space I34 of the stabilizer IIII is traversed by a shaft I36 which carries a ball-shaped transmitting member I31. Member I3! is engaged by the two pistons I and I3I. An arm I38 is mounted on shaft I36 outside of device IIlI.

For the purpose of explanation, it may be assumed that the entire hydraulic system of Fig. 2 is mounted on the spring supported body of a vehicle so that the plane of illustration represents a horizontal plane of the vehicle body, the traveling direction of the vehicle being indicated by the arrow A. It may further be assumed that the apparatus serves for stabilizing horizontal oscillations of the vehicle body transverse to the direc- As the vehicle is traveling in the direction of arrow A, a transverse movement of the vehicle body, for instance, in the direction indicated by the arrow B has the eifect of producing relative movement between the inertia weight I25 andthe enclosing and supporting structure of the control device. That is, due to its inertia, the weight I25 lags behind the movement of the vehicle body and moves downward relative to the illustration in Fig. 2. Thus the valve structure is shifted in the upward direction so that the flow areas of valve openings III and II! are diminished and those of valve openings I I3 and I I5 are increased. As a result, the pressure in cavity I08, duct I52 and pressure space I32 is reduced, and the pressure in cavity IE9, duct I83 and pressure space I33 is increased. lhe previously balanced piston assembly of the device IIiI is shifted in the up ward direction so that arm I33 is turned clockwise, i. e., also in the upward direction.

When the oscillationof the vehicle body to be stabilized is in opposition to the arrow B, the just-mentioned pressure control is reversed so that the arm I38 turns counterclockwise. In summary, in the system according to Fig. 2, a movement to be stabilized has the effect of producing a movement in the same direction of the free end of arm I38.

Referring now to Fig. 3, it will be explained how such movement of arm I33'is used for counteracting and stabilizing the undesired oscillation.

In Fig. 3, the wheel and axle structure of a rail vehicle is denoted by MI. The axle structure is journalled in journal boxes I42 and I63 which form part of a structure on which vehicle springs I45 and E55 are supported. A truck frame I rests on springs I and I45. A spring plank I l-l is movably suspended from the truck frame I46 by means of swing links I48 and I49 and serves as a support for another set of springs I and I5I. A bolster I52 is supported by springs I55 and 'I5I and serves to support the vehicle body proper, denoted by I53. A swivel bearing I54 between bolter I52 and body I53 permits annular movement of the body relative to bolster and truck. The spring suspension elements of the truck per-- mit vertical oscillations of the unsprung wheeland-axle structure relative to the car body and prevent the body from being unduly affected by road shocks. The swing suspension, also permits relative movements between the unsprung wheeland-axle structure and the car body in the horizontal direction transverse to the direction of travel as indicated, for instance, by-the arrow B. As mentioned above, the system accordingto Fig. 2 may be used for stabilizing such horizontal oscillations. To this end, the control device IEII is mounted on the bolster I52 and its arm I38 is connected by a rigid link I55 with the truck frame I45. -When the bolster I52 and the vehicle body I53 move in the direction of the arrow B (Fig. 3), such movement, if unopposed, would cause the link I55 to push against the arm I38 in the direction opposite to that of the arrow B. As explained, however, the inertia-controlled stabilizing device lei imposes on the arm a force causing its peripheral end to move in the same direction as the arrow B. Consequenly, the original tendency to move is immediately counter acted and substantially eliminated. a matter of fact, the system is capable of sensing any tendency of the vehicle body to move horizontally transverse to the direction of travel and imposes on the stabilizing elements the forces necessary to prevent an appreciable deflection.

Fig, 3 shows also two stabilizing cylinder-andpiston devices I56 and I5! linked between the bolster I52 and the journal structures I42 and I 43, respectively. These stabilizing devices may also be controlled by a hydraulic system according to the present invention to stabilize the vehicle body relative to vertical oscillations. The inertia weight of such a system must be arranged so that it responds to vertical movements of the control device. 7

Before describing further details, a comparison of the above-described system of Fig. 2 with the system previously disclosed in the above-mentioned application Serial No. 509,314 will be given in order to elucidate some performance characteristics and advantages of the invention.

The force amplification between main control valves and controlled device in hydraulic apparatus of the type here dealt with is the ratio of the output force developed by the piston of the controlled device (shock absorber piston) to the pilot force required for moving the main valves. In the previously disclosed system (Serial No. 509,314, Fig. 3), these forces are proportional, respectively, to the area (A of the shock absorber piston and the area (Av) of main valve so that the amplification (R) is fi R- In a hydraulic system according to the present invention (Figs. 1 and 2), the amplification factor (R) is also the ratio of the output force to the pilot force, but these forces are proportional to the area Ap of the piston (for instance, I3 in Fig. 2) to the difference in the areas A1 and A2 the two associated valve openings (for instance, at III and H3 in Fig. 2):

P A A Consequently, by properly selecting the area difference of valve openings III and H3 (or III area A2 (at H3 or II?) nearly equal to the area A1 (at III or H5). The amplification factor can even be made negative lif desired.

"through a .valve opening with the jchamber l "In further f'contrast to the systems previously disclosed, the idling losses (determined by .the average pressure drop .at the valves times the pump volume rate) .can :be reduced because the average pressure drop at the valves can bemade as low (as required by virtue .of the fact that the individual valve area is :no longer limited ,by the required amplification .factor.

'The overall time constant in the previously disclosed systems, as well as in systems according to the invention, is that of the pilot actuation; but the invention permits lowering vthis time .constant because for a given amplification ifaotor both the valve travel and 'force can -be lowered permitting the design of a faster acting 'pilot mechanism.

These advantages are "made "possible without incurring a reduction in the working e'fliciency ofthe system (ratio of volume rate of liquid --entering the controlled device :to volume rate of liquid entering the pump) which is not affected by the change in valve :design and valve performance.

An embodimentoi the inertia responsive .con- .trol device (pilot apparatus) I01 willnow pedescribed in detail ,with reference to "Figs. 4 to '8. In order to facilitate comparing these fi ures with the diagram o'fFig. '2, those'elements shown in.Figs. 4 and B that correspond to elements of the control .device -I0! according .to '2 .are .denoted by the same respective reference numeralsas those usedin Fig. 2-, and the ducts or conduits denoted in Fig. 2 by I02,.'Il03,105.10%, 4.050 and Ill .are designated by the same re- ,spective numerals in .Figs.-4 to-B.

.The pilot apparatus according .to A to 8 contains in number ,of ducts, ,passages, .cavities and otherenclosed chambers-.onspaces which are 'Ihese bodies are :.-firml;y--and *tig-htl-y ;,-attach-ed to each other and form (together we rigid housing a .-;suppont for 3a number of elements riessoribed'rhereinafter.

Bodiest52 02 and; 2 03 have an entrance chamber 5230511311 201 (Fig. :5) olosedrby zascoverescrewldflii ;or

259. :LEach entrance xcham-her has a threaded 'openin at which thevpumpputletrconduit [55b wr t-0601s attached. 581683785 2=I2 andc213 areiny serteddn bodi'es 252 and 263 respectivclmand and hence with" the ,conduit "I 550 Whichleatds-to municates with an intermediate pressure cham- "ber 2M whichgin turn, v.communioates' withithe neutral pressure space I20 within body 205 "in a manner to be deso-r i-bedAi-n a later place; and

communication with cavity L09 and is plugged at one end. The other end of bore zI'L- selected ior most convenient installation, receives the end of conduit 103 leading to ,the .con mlled device IOI (see Fig. 2). .An opening is provided be.- tween .cross bore 2II and intermediate pressure chamber 2I5. This opening is controlled ,by a check valve comprising a valve ball 2I9 and a spring -22I (Fig. 8). Due'to the spring bias and under the pressure obtainingin cross bore v ,2 I 'I and cavity I09, the check valve remains closed during normal operation. It opens only when, due to abnormal pressureconditions, the pressure in chamber .2 I5 becomes temporarily higher than that inthe cavity I09. The detail design of body 2.02 -(Fig. 5) is similar to .the features of body 203 shown inFig. 8, except .that the cavity 108 in body 202 is in free communication with the conduit :I-0'2 .of the .controlled device.

The neutral space I20 within body 205 (Fig. A) is free communication with a group of interconnected bores .222 of body 20I. These bores have three threadedopenings toward the exterior. One opening is plugged. The twoothers, selected .for convenient installation, receive .respectively the pump inlet conduit A05 and the neutral conduit I35 lead ng to theneutral space 1340f the controlled device (Fig. '2).

The two intermediate pressure chambers 2M and2l5 (Fig. 5) communicate with each other through bores 2.23, v224, 225 (Figs. 4, 5.) of body 20I. Bore 225 communicates with bores 222 (Fig. 4) under control by a spring biased pressurecontrol valve 226 adjustable bymeans of ascrew 22?. Valve 226 checks the jflow of liquid irom bores 222 .to the .intermediatepressure chambers 2H3, 2I5 but permits a flow in the reverse directionif the pressure in the intermediatechambers exceeds an adjusted value. Hence, the setting of valve .226 determines the pressure difference maintained between the intermediate chambers 2M, .2I5 and the neutral space I20.

The inertia weight I25 is mounted onan arm I26 whose pivot shaftIZIis journalled in ball bearings mounted onbody .204 (Figs. 4, 5) The centering springs 228 and 229 for weight rest against abutments .232 and 233, respectively, which are in threaded engagement with respec tive screws 2.3.4 and 235 mounted on body 204. The abutments are set for adjusting androughly balancing the centering force of springs 228, and 229. A correctbalance is secured by shiftingthe screw 235 with the. aid of a calibratingscrewifiii threaded .into a bore of body 2205 and accessible from the outside after, removal of a cover screw 1231 (Fig. 6) Excessive movementsof the inertia weight I25 areprevented'byabutment pins "238 .24'Iand have cup-shapedpackings248 and 12 59,

cavity I09 (Figs. 5,.B)-has another (upper) valve 5 bodies. I 22- and 11-23 rhas -two :va'lve graces to 4 .no-

soperatei with .the respective .two' valve sopenings :of each .cavity ES'TBXPIaiHQdvabEIVB :with. refereenceto. Fig. 2)

Across bore 2I-7L-inabodyi203. ('Eigaa) .issinwiree .movable the respective ;oa-.vities. Each of am respectively. The .two piston structures areinterconnected .by,..struts .251, 252, 253 (Figs. 4, 5) which pass through the respective bores i223, v224 and 225. Consequently, the two valve bodies I22 W and I23 form part of a rigid valve structure .and move in unison in the same manneras explained above with'reference to Figs. 1 and 2.

.The just-mentioned cylinder-andepiston delvioes disposed in the intermediate pressure chambers 2M and H5 representvariable-volume containers for actuating the valve structure.

.Each of "cylinders 246 and .241 communicates "through an orifice 256 or 251 with the intermediate pressure chamber 2I4 or H5 and has an outlet passage in communication with a duct 258 or 259 of body 20! (Fig. 5). Ducts 258 and 259 open into cavities 262 and 263, respectively (Figs. 5, 7), which are connected with the neutral space I20 through respective orifices 264 and 265. The flow areas of these orifices are controlled by poppet valves (pilot valves) 266 and 261 (Fig. 5). The two pilot valves are controlled in inverse relation to each other by a teeter bar 268 actuated 'by the inertia weight I25. When the inertia weight is in the illustrated center position, the flow areas of both pilot valves are equal. Then, the pressure obtaining between the orifices 256 and 264, i. e., within cylinder 246, is equal to the pressure obtaining between the orifices 251 and 265, i. e., within cylinder 241. Consequently, the force imposed by the pistons 244 and 245 on the valve structure are balanced, and the valve structure is normally in the illustrated centered position. When the inertia weight deflects from the center position, one pilot valve reduces its flow area and the other increases its flow area. The pressures in the cylinders 246 and 241 become dilferent from each other so that one piston moves inwardly and the other, outwardly of the appertaining cylinder. As a result, the valve assembly moves one or the other way depending upon the direction of weight deflection. The hydraulic transmission between inertia weight and the compound main valves represents a power multiplying or amplifying system. That is, small variations in force or displacement imposed on the pilot valves cause proportionate variations of amplified forces or displacements to occur at the main valves. Hence, the device according to Figs. 4 to 8 provides amplification in addition to that inherent in the hydraulic system of the main valves. It may be mentioned, however, that for many purposes, including the control of stabilizing equipment, the amplification obtainable by the main valve system is amply sufficient so that the inertia weight may be directly linked to the main valve structure thus permitting a considerable simplification of the device. Such a simplified control device, though equipped with condition-responsive control means other than an inertia weight, will be described below with reference to Fig. 9.

For inertia controlled vehicle stabilizing equipment a control performance proportional to the velocity of the movements to be stabilized is usually desirable. Since the movements of an inertia weight relative to its support are proportional to acceleration if the weight is subjected to an elastic bias only, damping means are provided to receive the preferred velocity-proportional deflection. These damping means, as shown in Fig. 5, are disposed and designed in the following manner.

Body 284 has two coaxial bores 212 and 213 which form dashpot cylinders and are covered by respective plates 21 and 215. Each plate has an orifice 216 or 211. Pistons 218, 219 with cup-shaped packings are movable in the cylinders and are interconnected by a rod 2813. Rod 288 passes through an opening in Weight arm I26 (Figs. 4, 5) and is pivotally linked to arm I 26 by a shaft 28!. Rod 288 may consist of two separate pieces, each being attached at one end to the respective pistons 218 and 218 while the other ends of the rod pieces are pivoted on pin 28I which then forms a hinge between the two pieces. Cylinders 212 and 213 communicate through an orifice 282 or 283 and a duct 284 or 285 with a cavity 286 or 281 (Figs. 5, 7) which is hydraulically connected to the intermediate pressure chamber 2I4 or 2I5 (Fig. 5). Hence, there is a steady flow of liquid from chamber 2 I 4 through a bleeder passage 286-284282212-216 to the neutral pressure space I28. A similar bleeder passage 281285-283213-211 leads from intermediate pressure chamber 2 I5 to neutral space I26. Any movement of Weight I25 about its center position causes the dam-per pistons 213 and 218 to reduce the enclosed volume of one cylinder and to increase that of the other cylinder. The expanding cylinder space draws liquid through the orifices 216, 282 or 211, 283 and the compressed cylinder space expells liquid through the respective orifices so that the piston movements are damped. In one orifice of each cylinder the flow of liquid clue to piston movement is in the direction of the steady flow from the intermediate pressure chamber to the neutral space and hence reduces the latter flow, while in the other orifice the two fiow components are in opposition to each other, so that at this point the continuous flow from the intermediate chamber to the neutral space is increased. Under these conditions the damping effect is independent of changes in Viscosity of the liquid and hence affords a substantially constant damping characteristic. For further elucidating this efiect, it may be mentioned that the flow of oil through the orifices 216 and 211 never reverses in direction. On the expanding side, for example at orifice 216, the flow through the orifice is reduced and the pressure in cylinder space 212 is increased. At the same time, the flow through orifice 211 is increased and the pressure in cylinder space 213 is decreased. The difference in pressure is nearly proportional to the velocity of the pistons, and the resulting force is the damping force. The existence of a steady flow of liquid through the cylinder spaces has the further effect that the cylinders are automatically filled when the source of pressure liquid is put in operation, and that any initially enclosed air bubbles are scavenged out of the cylinder. Besides, by adjusting or selecting the flow resistance of the bleeder passages and orifices so that the average pressure in the cylinder is not higher than the mean value of the modulated pressure, the leakage losses and the friction at the cupshaped packings can be kept at a minimum.

Due to the steady flow of liquid from the intermediate pressure chambers 2I4, 2I5 (Fig. 5) to the neutral space I28 through the bleeder passages of the actuating cylinders 246, 241, the latter cylinders are also scavenged by a steady flow of liquid and the force imparted to their respective pistons is proportional to the pressure variation or movement of the pilot valves. In order to reduce leakage losses and friction at the cup-type packings 248, 249, the average pressure within the actuating cylinders may also be adjusted to be not appreciably higher than the mean modulated pressure.

The above-mentioned design and pressure adjustment of the bleeder passages is in accordance with the copending application Serial No. 794,145 of L. B. Lynn, assigned 'to the assignee of the present invention, and it should'be understood that other features disclosed in the copending application may also be applied in conjunction with apparatus according to the present invention.

Theembodiment of the invention illustrated in Fig. 9 exemplifies an application for the control of fabricating machinery. More specifically, the illustrated apparatus represents the control portionof a shuttle drive for weaving looms. Such a shuttle drive is illustrated and described more in detail in the copending application Serial No. 788,346 of S. J. Mikina which issued June '21, 1949 as Patent No. 2,473,896. However, for a complete understanding of the controlling apparatus according to the present invention, it suflices to know that the element to be controlled by the hydraulic system consists of a slotted lever 280a which is hinged at two pivot pins 2am and 282a, and, in order to perform its controlling operation, is to be alternately tilted about the pivot pins 2am and 282a,

The pivot pin 28kt is attached to a piston rod 283a, and pin 282a is attached to a similar rod 2840;. The appertaining pistons 285a, 286a are slidable in a cylinder 281a or 288a. The two cylinders are attached to a stationary supporting structure or machine frame 29! Each pivot pin and appertaining piston assembly is biased toward the illustrated position of rest by a spring .291 or 292.

The two cylinder and piston devices form part of a hydraulic apparatus designed in accordance with the invention. This apparatus is schernatieally represented by the simplified circuit diagram illustrated in Fig. '10 which may also be referred toflfor an understanding of the following description The pressure space b tw n he piston 235 and the bottom of cylinder 281dis in com u with a conduit 332. A similar conduit 3.93 "leads o the p essure spac between piston 236a and cylinder 288a. Liquid under pressure to be su plied to the conduits .302 and .393 is provided by a hydraulic power source 394 which may consist of a pump or of a pressure reservoir The source 3% has an inlet or return duct 305 split into two conduits .305?) and 305.0 and a pressure .duct .306, the latter being split into two conduits 39Gb and 3136c. A control device 391 has two cavities .368 and 30-9 and a neutral chamber 320. Each of these cavities has three openings. One opening is in communication with the conduit 302 or 303. The two other openings of each chamber communicate with the duct 386?) or 3950 and with the neutral chamber 329, respectively. Two valve bodies 322 and 323 in respective cavi ies 303 and 3% are each equipped with two valve elements for controlling the two latter openings of each cavity, as explained in the foregoing with reference to Figs. 1 and 2. The two 55 valve bodies :322 and 323 are interconnected by a rod 324 which raverses the neu ral chamber 3.20 and carries a magnetic armature 325 inside th chamb r. Two heli al springs. 528 and 329 res a ainst the armature 3.25 and hold it nor mally in centered position. 'I'Woelectromagnet co ls 3.30 and 33K arranged in chamber 325.! at both sides respectively of the armature 325 serve to displace the armature in opposition to the spring b as toward one or the other side, dependins upon which of the two magnets is more strongly energized. Energizing current is supplied to the magnet coils from terminals 332 which are connected to a suitable electric control device (not illustrated) to be actuated by the fabricating machinery in a predetermined phase relation to the operating cycle of the machinery.

As long as the armature 325 is in the illustrated center position, the pressures in the two cavities 308 and 309 are equal. When the magnet coil 13% is .-.energize'd above or 'more strongly than the magnet :coil 33!, the armature 32.5 is shifted toward the left. As .a result, the valve opening between cavity 3&8 and duct 'Siifib reduces its new area, and the valve between cavity 3%.? and .duct .3860 increases its flow area. As a result, the pressure in cylinder 233a above piston? 8 3a (Fig. 9) increases sufficiently to move the piston assembly downward in opposition to the iorceof spring 292. Consequently, the lever 23 x311. is now tilted clockwise about the pivot pin ifilmwhic'h remains stationary. When'the magnet coil 315i is energized alone or more strongly than coil 3%, the armature 325 moves toward the rig-ht and the pressure inthe pressure space of cylinder 28M is increased, while the pressure in the pressure space of cylinder 288a is reduced. Consequently, the pivot pin 252a, moves upward into the illustrated position and remains in that position while the pivot pin 284a moves also upward and turns the lever-280a clockwise about the pin 282a. 7

It will "be recognized from the circuit diagram of Fig. 10 that apparatus according to Fig. 9 maybe considered to have two individually operative control devices. The'control of each device is efiected by the valve displacement in only one of the two cavities 308 and 399.

It will he understood from the foregoing that in this specification the terms cavity, charm her and space are used merely for the purpose of distinction and convenient terminology, rather than for indicating difierences in size or structure. Similarly, the terms duct, conchili and "passage are not intended to denote necessary difierences in design; that is, these ducts and conduits and passages may either be formed by bores or other enclosed channels or the may consist of separate pipe connections.

It will be understood by those skilled in the art, after a study .of the present disclosure, that apparatus in accordance with the principles of our invention can be modified in various respects and may be realized by structural embodiments other than those specifically illustrated and described, without departing from the essence of the invention and within the essential features of the invention set forth in the claims annexed hereto.

We claim as our invention:

1. Hydraulic apparatus, comprising hydraulic powerdevice having a pair of ducts for circulating liquid, a hydraulic device to be controlled having another pair of ducts, a'control device having a housing with two cavities individually connected between the respective ducts of one of said pairs to form two hydraulically para-llelly arranged paths for the liquid, said two cavities being in communication with said respective ducts of said other pair, two movable valve means having continuously variable openings respectively and being disposed in said housing for controlling the flow of liquid through respective paths, said valve openings being both open under all normal operating conditions 'of said respective valves and having normally a flow area of medium magnitude and means interconnecting said respective valve means for controling them in inverse relation to each other to increase the flow area of one valve opening while correspondingly decreasing the flow area of the other valve opening.

2. Hydraulic apparatus, comprising liquid circulating power means having a pair of ducts, a

hydraulic device to be controlled having a pair of ducts, a control device having two cavities each having three openings, which are always open during the control operation of said device and of which two are flow-restricting'as compared with the third, said two flow-restricting openings of each cavity being in communication with the respective ducts of one of said pairs and the third opening being in communication with one of the respective ducts of said other pair of ducts, valve means adjacent one of said flow-restricting openings of each cavity and normally positioned relative to said opening for a flow resistance of medium magnitude, said valve means in each cavity being movable for varying flow resistance between finite magnitudes, and means interconnecting said respective valve means for simultaneously controlling them in inverse relation to each other so as to increase the flow of liquid through one cavity when decreasing the flow through the other cavity.

3. Hydraulic apparatus, comprising a positive displacement pump for liquid under pressure having an inlet conduit and an outlet conduit, a hydraulic device to be controlled having a pair of ducts, a control device having two cavities each having three openings which are always open during the normal control operation of said device and of which two are flow-restricting as compared with the third, said two flowrestricting openings of each cavity being in communication with said respective conduits and the third opening being in communication with one of the respective ducts of said other pair of ducts, movable valve means adjacent one of said flowrestricting openings of each cavity for varying the effective flow resistance of said opening, and rigid means firmly interconnecting said respective valve means for simultaneously controlling them in relation to each other so as to increase the flow of liquid through one cavity when decreasing the flow through the other cavity.

4. Hydraulic apparatus, comprising a source of hydraulic pressure having an inlet conduit and an outlet conduit, a hydraulic device to be controlled having two pressure spaces and a member movable in response to differential pressure'of said spaces; a control device having two cavities connected in hydraulic parallel relation to each other between said two conduit and being individually in communication with said respective pressure spaces, two valves disposed in each cavity for controlling communication between-said cavity and said two respective conduits, said valves being always open during normal control operations of said device and having variable flow areas respectively, and means rigidly interconnecting said four valves for controlling them in a fixed relation to one another so that an increase in flow area of one is accompanied by a decrease in flow area of the other valve in the same cavity and by decreased flow area and increased flow area respectively of the corresponding two valves in the other cavity.

5. Hydraulic apparatus, comprising a source of hydraulic pressure havingan inlet conduit and an outlet conduit of which one is split into two branches; a hydraulic motor having two motor conduits and a movable member controllable in response to the difierence in pressures in said respective motor conduits; a control device having two cavities in communication with said respective motor conduits and connecting said respective conduit branches with said other source conduit, and four always open regulating valves disposed between said two cavities and said two conduit branches respectively and between said respective cavities and said other conduit, each of said valves having a flow resistance variable between high and low finite values respectively, said four valves being rigidly interconnected so that increased resistance of one valve is accompanied with decreased resistance of the other valve in the same cavity and decreased resistance and increased resistance respectively of the corresponding two valves in the other cavity.

6. Hydraulic apparatus, comprising a source of hydraulic pressure having an outlet conduit for providing liquid under pressure and a return conduit for the liquid; a pressure responsive hydraulic device having a cylinder and two pistons forming together with said cylinder a neutral space between said pistons and two pressure spaces on the respective other sides of said pistons, said neutral space being in communication with said return conduit and containing a movable member engaged by said pistons to be moved by said. pistons in response to the difference in pressures in said respective pressure spaces; a control device having two cavities individually disposed between said outlet conduit and said inlet conduit to form two hydraulically parallelly arranged paths between said two conduits, said cavities being in communication with said two pressure spaces, two always-open valves of gradually variable flow-resistance disposed in each cavity to control the communication between said cavity and said two respective conduits, and means rigidly connecting said four valves with one another so that increased resistance of one valve is accompanied by decreased resistance of the other valve in the same cavity and decreased resistance and increased resistance respectively of the two corresponding two valves in the other cavity.

7. Hydraulic apparatus, comprising a source of hydraulic pressure having an inlet conduit and an outlet conduit of which one is split into the branch conduits; a control device having two cavities communicating with said respective pressure spaces, each cavity having two aligned conical openings in communication with said two respective conduits, a body disposed in each cavity between said openings and movable in the alignment axis of said openings, said body having two conical valve faces adjacent to but always spaced from said respective openings so that movement of said body in one direction increases the flow resistance at one opening and decreases the flow resistance at the other opening, and rigid structure firmly connecting said two bodies with each other for controlling them to move simultaneously so that a variation of the flow resistance at the openings of one cavity is accompanied by inverse variation of the flow resistances at the corresponding respective openings in the other cavity.

8. Hydraulic apparatus, comprising a single hydraulic pressure source having two ducts for circulating liquid under pressure; a hydraulic device to be controlled having two relatively movable members and spring means biasing said members in one direction relative to each other, said members forming together a liquid-receiving space to move in the other direction when the pressure in said space exceeds the force of said biasing means; a control device having a cavity in free communication with said space, said cavity having two valve-controlled openings in always open communication with said respecassua e tive ducts, two movable valve members disposed in cooperative relation to said respective open ings and connected with each other for varying the efiective flow areas of said respective valve openings in inverse relation to each other through a range above a finite minimum magnitude.

9. Hydraulic apparatus, comprising a single hydraulic pressure source having two ducts for circulating liquid under pressure; a hydraulic device to be controlled having a cylinder and a piston formingtogether two enclosed spaces for liquid on both sides respectively of said piston and being movable relative to each other in dependence upon the difierence of the pressures in said respectivespaces, one of said spaces being in always open communication with only one of said ducts; a control device having a cavity with three openings of which one is in always open communication with said other space, the two other openings being in always open communication with said respective ducts, twomovable valve members disposed adjacent said two other openings for varying the effective flow areas or said other openings respectively, and control means connected with said two valve members for moving them together to vary said areas ininverse relation to each other.

10. Hydraulic apparatus, comprising a hydraulic pressure source having a pressure duct and a return duct for circulating liquid under pressure; a device to be controlled having a cylinder and a piston forming together two enclosed spaces for liquid on both sides respectively of said piston and being movable relative to each other in dependence upon the difierence of the pressures in said respective spaces, one of said spaces being in free communication with said return duct; a control device having a cavity with three openings of which two are in always open communication with said respective ducts while the third opening is in always open communication with said other space, a valve body movably disposed in said cavity and having two valve elements adjacent said two openings respectively so that movement of said body varies the efiective flow areas of said two openings in inverse relation to each other, and com dition-responsive control means connected to said body for controlling said body.

11. Hydraulic control apparatus, comprising a housing having first duct means open toward the exterior for supplying liquid under pressure, second duct means open to the exterior for the discharge of liquid, two outlet ducts open to the exterior for providing respective hydraulic pressures of controllable diiierential value, two cavities within said housing, each cavity having three openings communicating with said first duct means and said second duct means and an individual one of said outlet ducts respectively, a valve structure disposed in each cavity and having two valve elements adjacent the two respective openings that communicate with said first and second duct means, said valve elements being always spaced from said respective two openings during normal operation of the apparatus and being positioned relative to said two respective openings to normally maintain respective flow resistances of medium magnitude at said two openings, and said valve structures being movable for varying said flow resistances between finite magnitudes in inverse relation to eachother, and connecting means joining said two valve structures so that movemet of one structure toward reduced flow resistance of one opening in one cavity is accompanied by movement of the other structure toward increased flow resistance of the corresponding opening in the other cavity.

12. Hydraulic control apparatus, comprising a housing having pressure duct means open toward the exterior for supplying liquid under pressure, a neutral duct open to the exterior for the discharge of liquid, two outlet ducts open to the exterior for providing respective hydraulic pressures of controllable differential value, a neutral chamber in communication with said neutral duct, two cavities in communication with said respective outlet ducts, each of said cavities having two aligned openings in communication with said pressure duet means and said neutral chamber respectively, a valve body disposed in each cavity and movable in the alignment axis of said two openings, each valve body having two valve elements adjacent said respective two openings so that movement oi said body varies the flow areas of said openings in inverse relation to each other, said valve elements being spaced from said respective openings in all operating positions of said valve body, and said valve body having normally a given position in which said flow areas have, a medium magnitude, structure rigidly interconnecting said two bodies and traversing the twoopenings that communicate with said neutral duct, and condition-responsive control means disposed in said neutral chamber and connected to said structure for controlling said bodies to move in a fixed relation to each other so that increase in area of one of said latter two openings is accompanied by decrease in area of the other opening.

13. Hydraulic control apparatus, comprising a housing having pressure duct means open toward the exterior for supplying liquid under pressure, a neutral duct open to the exterior for the discharge of liquid, two outlet ducts open to the exterior for providing respective hydraulic pressures of controllable difierential value, a neutral chamber in communication with said neutral. duct, an intermediate pressure chamber having a bleeder passage communicating with said neutral chamber, two cavities in communication with said respective outlet ducts, each of said cavities having two valve openings in com.- munication with said pressure duct means and said intermediate chamber respectively, two interconnected valve elements disposed in each cavity and being together movable relative to said two valve openings fOr varying the flow resistance values of said two valve openings in inverse relation to each other, connecting structure joining the valve elements in one cavity with those in the other cavity and extending through said intermediate pressure chamber, a variable-volume container disposed in said intermediate pressure chamber and connected with said structure for controlling said valve elements, said container being hydraulically associated with said bleeder passage to be actuated in dependence upon the pressure in said passage, and condition-responsive control means disposed in said neutral chamber and having pilot valve means for controlling said passage to vary the pressure therein.

14. Hydraulic control apparatus for vehicle stabilizers, comprising a housing having pressure duct means open toward the exterior for supplying liquid under pressure, a neutral duct open to the exterior for the discharge of liquid, two

outlet ducts open to the exterior and adjusted for attachment to stabilizing equipment to provide therefor respective hydraulic pressures of controllable diiferential value, a neutral chamber in communication with said neutral duct, an intermediate pressure chamber having bleeder passages communicating with said neutral chamber, two cavities in communication with said respective outlet ducts, each of said cavities having two valve openings in communication with said pressure duct means and said intermediate chamber respectively, two interconnected valve elements disposed in each cavity and being together movable relative to said two valve openings for varying the flow resistance values of said two valve openings in inverse relation to each other, connecting structure joining the valve elements in one cavity with those in the other cavity and extending through said intermediate pressure chamber, actuating means disposed in said intermediate pressure chamber and connected with said structure for moving the latter, control means connected with said actuating means for controlling the latter and including an inertia mass movably disposed in said neutral chamber, and hydraulic means disposed for biasing the movement of said mass in order to obtain a desired performance characteristic and having a variable volume container in mechanical connection with said mass and in hydraulic connection with one of said bleeder passages so as to be subjected to pressure dependent upon the pressure difference between said intermediate pressure chamber and said neutral chamber.

15. Hydraulic control apparatus, comprising a housing having pressure duct means open toward the exterior for supplying liquid under pressure, a neutral duct open to the exterior for the discharge of liquid, two outlet ducts open to the exterior for providing respective hydraulic pressures of controllable differential value, a neutral chamber in communication with said neutral duct, two cavities in communication with said respective outlet ducts each of said cavities having two aligned openings in communication with said pressure duct means and said neutral chamber respectively, a valve body disposed in each cavity and movable in th alignment axis of said two openings, each valve body having two valve elements adjacent said respective two openings so that movement of said body varies the flow areas of said openings in inverse relation to each other, said valve elements being spaced from said respective openings in all operating positions of said valve body, and said valve body having normally a given position in which said flow areas have a medium magnitude,

18 a rigid structure extending through said neutral chamber and rigidly interconnecting said two bodies for moving them in a fixed relation to each other so that increase in flow area of an opening'in one cavity is accompanied by decrease in flow area of the corresponding opening in the other cavity, and an electromagnet disposed in said neutral chamber and having an armature mounted on said structure for controlling said valve bodies.

16. Vehicle stabilizing apparatus, comprising a device having two relatively movable members defusing together two pressure spaces to control relative movement between said members in response to the difierential value of the pressures in said respective spaces; a positive displacement pump for liquid having a pressure conduit and a return conduit; a control device having a neutral chamber in communication with said return conduit and two cavities in communication with said two respective pressure spaces, each cavity having two valve openings communicating with said pressure conduit and said return conduit respectively, a valve body disposed in each cavity and having two valve elements to cooperate with said respective two openings so that movement of said body varies the flow areas of said respective openings in inverse relation to each other, said valve elements being spaced from said respective openings in all operating positions of said valve body, and said valve body having normally a given position in which said fiow areas have a medium magnitude, said two valve bodies being interconnected for simultaneous operation so that increase in flow area of one opening is accompanied by decrease in flow area of the corresponding opening in the other cavity, and an inertia mass movably suspended in said neutral chamber and connected with said structure for controlling it in response to movement to be stabilized to cause said device to produce relative movement of said members in the stabilizing direction.

LAWRENCE B. LYNN. STANLEY J. MIKINA.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 955,852 Coyle Apr. 26, 1910 1,454,396 MacDonald May 8, 1923 1,992,048 Temple Feb. 19, 1935 2,229,530 South Jan. 21, 1941 2,378,497 Phillips June 19, 1945 

